The authors regret that some errors appeared in the original version of this article. The incorrect staining image was used in Figure 7 B. The correct image is shown below. In addition, in the Results section entitled Intestinal microbiota-induced IL-15 production promotes intestinal Th17 cell polarization, the second sentence should read “IL-6 expression in the small instenstine was increased after PR8 infection.” Finally, in Table S1, the correct primer sequences used for the Bacteroides are as follows: 5ʹ-GGTTCTGAGAGGAGGTCCC-3ʹ (forward) and 5ʹ-GCTGCCTCCCGTAGGAGT-3ʹ (reverse). In addition, Figure 1 B has been updated in the html and pdf versions of this article since initial publication. The print version remains unchanged. These changes do not alter the conclusions of the paper.